1. Field of the Invention
The present invention relates to a treatment agent for salt-containing organic waste liquid, a salt concentration-reducing agent, a treatment method for salt-containing organic waste liquid, and an entrapment immobilization carrier.
2. Description of the Related Art
From the viewpoint of environmental protection, there has recently been an increased demand for a waste liquid treatment method capable of reducing a COD (chemical oxygen demand) value which is one index of water quality.
Methods for treating waste liquid include: biological treatment methods such as an activated sludge method and a rotating disc method; and physicochemical treatment methods such as an aggregation method, a precipitation method, an activated carbon filtration method, and a membrane filtration method. Among them, biological treatment methods, especially an activated sludge method, have recently been popular as a method for treating domestic waste liquid and industrial waste liquid.
In such biological treatment methods, waste liquid is cleaned by a mixed microorganism system such as bacteria, protozoan organisms and metazoan organisms.
In one method proposed as the biological treatment methods, organic contaminated waste liquid is brought into contact with activated sludge rich in metazoan microorganisms belonging to the Philodina sp. (see Japanese Patent Application Laid-Open (JP-A) No. 07-155791).
However, metazoan organisms generally have a problem that they grow more slowly than protozoan organisms do and have difficulty in rapidly treating waste liquid. Also, in use of an activated sludge method, there are problems such as occurrence of a so-called bulking phenomenon that involves degradation in aggregation or precipitation due to abnormal swelling of sludge, and generation of a large amount of extra sludge. Furthermore, the organisms belonging to the Philodina sp. are freshwater organisms belonging to Rotatoria, and when used to treat salt-containing organic waste liquid, the organisms belonging to the Philodina sp. are killed due to salt stress in activated sludge where they are a dominant species. As such, when salt is contained in waste liquid to be treated by the biological treatment methods, organisms used in the methods are plasmolyzed due to the difference in osmotic pressure and are killed, which raises a problem of considerably reducing their capability of treating waste liquid.
The salt-containing organic waste liquid is, for example, waste liquid of marine waste, and jellyfish has been problematic as the marine waste.
Jellyfish floating in, for example, seawater occurs in immense numbers mainly in warmer months, causing various damages. In particular, jellyfish has inflicted enormous damage on the coastal fishing industry such as set net fishery. In addition, seaside plant facilities such as power plants or steel plants require large amounts of cooling water and employ seawater as the cooling water. These facilities are therefore provided with water intakes for seawater. However, there have arisen problems associated with damage caused by jellyfish that clogs these water intakes to restrict or stop the taking of water so that the operation of the facility is hindered. Once such jellyfish has been landed, it becomes industrial waste which cannot be released or disposed of in ocean as is. Thus, various attempts have been made to develop various methods for disposing of the landed jellyfish (see, for example, JP-A Nos. 2001-300505, 2000-5738, 11-244833, 2003-145196, 2001-198566, 2003-53303, 11-179327, 2001-95564 and 2002-136952, and Doi Hiroyasu, Oka Tatuszo, Yoshiaki Nonomura, Bulletin of the Society of Sea Water Science, Japan, 2007, Vol. 61, No. 6, pp. 342-351).
Nevertheless, the salt contained in salt-containing organic waste liquid such as waste liquid of decomposed jellyfish prevents the salt-containing organic waste liquid from being efficiently decomposed and disposed of. Biological treatments using, for example, enzymes and/or microorganisms can perform decomposition disposal treatment more efficiently than in the mechanical disposal treatment, but involves problems due to the presence of salt that sufficient enzymatic activity cannot be obtained and microorganisms are killed.
Therefore, conventionally, waste liquid of decomposed jellyfish has been diluted with freshwater and then subjected to decomposition disposal treatment with, for example, activated sludge. In this case, a large amount of freshwater has to be used for dilution, which is not efficient.
In proposed alternative methods, a carrier on which yeast and/or bacteria have been immobilized is used to treat salt-containing organic waste liquid (see JP-A No. 2007-000863 and Doi Hiroyasu, Mikio Takeda, Oka Tatuszo, Yoshiaki Nonomura, Bulletin of the Society of Sea Water Science, Japan, 2006, Vol. 60, No. 6, pp. 426-433).
Even with this method, however, it takes 2 days to 3 days to reduce the COD value of waste liquid of enzymatically decomposed jellyfish by about 80%, which is problematic in view of long treatment time required.
Therefore, at present, demand has arisen for provision of a treatment agent for salt-containing organic waste liquid, a salt concentration-reducing agent, a treatment method for salt-containing organic waste liquid, and an entrapment immobilization carrier that are highly safe and can simply, efficiently and inexpensively treat organic waste liquid containing salt for a short time at low energy without the need of a special apparatus.